This invention relates to improvements in weather caps for exhaust pipes.
Weather caps for exhaust pipes which are pivotally attached to the top of vertical exhaust pipes to prevent entry of rain, dust and the like when the engine is not operating are widely used and are disclosed in more detail for example in U.S. Pat. Nos. 2,983,216 Stade et al and 4,059,045 McClain et al.
One problem with weather caps of the above type is that they tend to create undesirable noise caused by metal to metal contact as the cover is provided by the exhaust of the engine. One attempt to solve such problems is disclosed in U.S. Pat. No. 4,255,928 Jones et al.
While the solutions posed by the above United States patent successfully reduce the noise created by oscillation of the weather cap under the influence of the exhaust, they require modification of the clamping assembly of the cover and of the balance arm and, at least in the case of the second embodiment, the bumper member has been found to be prone to fracture under the stresses applied to the bumper by the oscillatory weather cap.
It is the object of the present invention to provide a means for reducing noise in weather caps for exhaust pipes which requires less modification to the supporting structure for the cap and which is less likely to fracture in use.
According to the invention there is provided a weather cap comprising a mounting collar adapted to surround the exhaust pipe to be protected, a clamping bolt for bringing the ends of the collar together to clamp the collar in position around the exhaust pipe, mounting arms extending from the ends of the collar and between which a bearing supporting a counterbalance arm and cap is secured, characterized by resilient bumper means supported by the clamping bolt and including a portion projecting above the uppermost edge of the collar so as to be engaged by the counterbalance arm or cap when in the rest position and a portion projecting below the clamping bolt so as to be engaged by the counterbalance arm when in the fully open position, said bumper having means engaging one arm of said mounting collar to prevent rotation of said bumper on said bolt.
It will be appreciated from the above that by using the clamping bolt to support the bumper, the only modification to the weather cap is the addition of the bumper. Thus, contrary to the embodiments disclosed in U.S. Pat. No. 4,255,928, each of which requires substantial modification to the clamping collar of the cap structure, the silencing effect of the bumper is achieved at a minimal additional cost. Similarly, since the bumper is evenly supported throughout its length by the clamping bolt, specific regions of stress, such as occur with the embodiment of FIG. 8 of the above U.S. Patent, are less likely to occur.
The invention also provides a resilient bumper for an exhaust weather cap comprising an elongate head portion and a downwardly extending portion positioned centrally of said head portion, a bore in said downwardly extending portion for receiving a weather cap clamping bolt, said head portion being dimensioned to extend above the uppermost edges of a clamping collar for said weather cap so as to engage at least one arm of said collar to prevent rotation of said bumper, said downwardly extending portion being dimensioned to extend below said clamping collar.